The term "ceramic fibers" as used herein means polycrystalline metal oxide fibers having a high melt temperature typically in excess of 3,000.degree. F. Such fibers generally contain aluminum oxide or calcium oxide and silica, as well as smaller amounts of other metal oxides, such as ferric, titanium and magnesium. A typical ceramic fiber will comprise, for example, in excess of 30% aluminum or calcium oxide, in excess of 45% silica, with any remainder as other metallic oxides. Specific examples of compositions for ceramic fibers include the following:
______________________________________ EXAMPLE 1 EXAMPLE 2 EXAMPLE 3 ______________________________________ Al.sub.2 O.sub.3 47.5% 45% 10% CaO 35% SiO.sub.2 49% 52% 45% Fe.sub.2 O.sub.3 1% 1% 3% TiO.sub.2 2% 2% 2% Misc. Metal Oxides MgO 0.5% Trace .5% ______________________________________
The fibers are made by several processes, one of which involves the formation of a melt at oven in excess of 3200.degree. F., and then contacting a spinning or slinging wheel or high velocity gas with the melt to produce individual fibers, which are then cooled and collected. Various compositions for ceramic fibers and methods for making the same are described in the following patents: U.S. Pat. Nos. 2,557,834; 2,674,539; 2,699,397; 2,710,261; 2,714,622; and 3,007,806.
Ceramic fibers of the foregoing nature have a variety of present and proposed uses, particularly as fillers and insulating media. The use of such fibers, however, has been somewhat limited because of their limited flexibility, strength, abrasion resistance and most critically their lack of dispersibility in water or other liquids. For example, ceramic fiber of typical size distribution as currently produced will not form a stable slurry or dispersion in water, even with the addition of surface active agents and requires high shear agitation to produce even moderately uniform suspensions. Due to the shear sensitivity of this class of fibers, the fiber length is reduced drastically in the process which reduces their ultimate produce thermal value and product strength.
The ability to disperse fiber would be desirable from the viewpoint of producing a better variety of shapes or forms with improved physical properties of strength and uniformity. Such products include papers, webs, foams, molded shapes, small yarns and the like.